Archiving Experiments Based on Radiological Images Fred Prior, Ph.D. Mallinckrodt Institute of Radiology Washington University School of Medicine

Radiology Image Archives Standard clinical practice to archive radiological images permit comparison with future studies, determine disease progression or response to therapy. minimal metadata required for visual inspection of images by human observer It is not common to archive research images and metadata to either permit reuse of the image data for new experiments or an experiment to be repeated. Even though data sharing has been an NIH requirement since 2003 To repeat a quantitative imaging experiment requires an extensive amount of information to be carefully collected and stored in addition to the imaging data itself.

Documenting Image Based Experiments Hypotheses being tested Description of the experimental design Characteristics of the populations being studied Acquisition protocol Stimulus and design matrix Positioning and calibration Reconstruction and correction Registration information Measurements and analyses Type of measurement taken (e.g. SUV) Derived images (e.g. fMRI, DTI) Data formats Image data Annotations/ derived measurements

BMD precision is affected by kVp, table height, reconstruction kernel, etc. To control for these variables a calibration phantom is placed in the scan volume during each imaging session. Accurate determination of BMD from CT image data requires a mapping from measured intensity to known concentrations of Ca Hydroxyapatite Apparent BMD of the Bones of the Foot Apparent BMD (gm/cc) Ca Hydroxyapatite Hounsfield Units

Image Segmentation and Structural Analyses

Task-based Functional Imaging fMRI scans require information about the stimulus and the time sequence of stimulus presentation and image acquisition What was the design matrix for the experiment – event related, block, etc. fcMRI may be analyzed by seed-based correlation or ICA The analysis technique must be documented Data courtesy Linda Larson-Prior, Ph.D.

Federated Image Storage & Retrieval

SumsDB SumsDB was created by David Van Essen to manage functional imaging data It stores both images and metadata together in a common database Published papers describe experimental methods and analyses Figures link to the data that was used to produce them